Systems that provide assistance in driving are now common in the latest motor vehicles and are experiencing rapid development.
Adaptive speed controls (ACC) have been known for some years. Such an assistance mode adjusts the speed automatically so as to maintain a constant safe spacing with the vehicle ahead of the user based on information collected about this vehicle (in particular its distance and speed of approach) using one or more radar, lidar or infra-red sensors.
Dynamic involuntary lane departure warning systems are also known, particularly from US 2013/0096767. These systems, generally known by the acronyms ALKA (for “Active Lane Keep Assist”), LKAS (for “Lane Keep System Assistance), ALA (for “Active Lane Assist”) or ALC (for “Active Lane Control”), detect the marking lines on the ground using sensors and/or optical cameras, and act dynamically on the vehicle when the vehicle strays from its lane. The driving assist system will then automatically correct the direction of the vehicle and/or will activate the braking system.
More recently, systems proposing completely automated driving modes have emerged in order to relieve the driver in dense traffic situations on roads with separate carriageways where the speed of the vehicle is reduced.
This is particularly the case for assist modes for driving in congestion (better known under the English acronym TJC for “Traffic Jam Chauffeur”) intended to relieve the driver in dense traffic or traffic jam situations (speeds lower than 50/70 km/h) on roads with separate carriageways (motorways and expressways).
One can also mention driving assistance modes on motorways commonly referred to by the acronym HC (for “Highway Chauffeur”) that can entirely relieve the driver in fluid traffic situations (at a speed close to the lawful limit) on roads with separate carriageways.
In the event of degradation of the ambient driving conditions requiring a return to the manual driving mode, the TJC or HC types of assistance are able to maintain fully automated guidance of the vehicle for a rather long transition period of ten seconds before returning to the manual mode of control, so that the driver is not required to keep his eyes fixed on the road and can engage in other things (making telephone calls, looking at a film via the information-entertainment system of the vehicle, launching a video game on a computer or a touch pad, reading of book or a magazine, etc.).
Lastly, driving assistance modes on motorways, commonly referred to by the acronyms HAD for (“Highway Automated Driving”) or AHDA (for “Automatic Highway Driving Assist”), have lately appeared and they are also able to relieve the driver on roads with separate carriageways but without restrictions on use relating at the speed of the vehicle or the density of the road traffic.
In such a mode, fully automated guidance can only be maintained over a short transition period (typically between 1 and 3 seconds) in the event of degradation of the driving conditions requiring a return to manual control. It is thus essential for the driver to permanently maintain a certain level of attention on the road so as to be ready to instantaneously retake control of the vehicle.
In vehicles equipped with such automated driving systems, it is essential to provide communication interface capable of informing the driver of the state of this system.
U.S. Pat. No. 9,134,729 discloses an automated driving system for motor vehicles comprising a visual communication interface including several light indicators on the steering wheel as well as numerous displays located on the instrument panel capable of emitting light signals of various colors depending on the state of the system.
However, drivers have found such a visual communication interface to be hard to use and it may in turn provoke inappropriate, potentially dangerous reactions.